This invention relates deflectors for use with rain gauges, or rain gauges with deflectors used for enhanced and more accurate measurement of rainfall.
Rain gauges are common instruments for measuring the extent of rainfall, and come in a variety of shapes and sizes. For example, one form of rain gauge may comprise a hollow conically-shaped housing, open at its wide end which faces upwardly to collect the rain, with calibrated indications down the length of the gauge to facilitate easy reading of the amount of precipitation. One advantage of a conical shaped structure with a wide open end and a pointed lower end is that the larger surface area will be exposed to rain and therefore, based on the size of the rain gauge, capture more water as well as provide a broader indication of the amount of rain. However, cylindrical or other shaped rain gauges are equally effective and in common use.
Existing rain gauges have, of course, fixed surface areas for admitting rain, and would usually be constructed with calibration markings down the side; these calibration markings are based on rain falling about parallel to the axis of the rain gauge, usually vertically, also at about 90.degree. to the horizontal. These existing rain gauges would, therefore, be reasonably accurate for rain falling vertically, but as the direction of rain changes with respect to the vertical, the amount of water being captured by admission through an open aperture at the top of the rain gauge would decrease. As an extreme, if rain were falling at an angle approaching the horizontal, very little or no rain would pass through the aperture into the rain gauge and the rain gauge would indicate no or very little rainfall. This is, of course, inaccurate.
Under normal circumstances, rain will fall at many different angles relative to the vertical, depending on the direction of the wind, and the force of the wind, at any given time. In rainstorms, it is not unusual for the force and direction of the wind to change from one moment to the next, impacting the amount of water captured by the rain gauge over a period of time. Thus, the amount of water captured by a rain gauge would decrease as a result of wind factors, even though the amount of rain falling may have been reasonably steady.